The Effect of Water Absorption on the Creep Behavior for Polymer Composite Materials

Abstract

In this investigation, a low cost, mechanically operated creep testing machine capable of determining the deformation property of material is developed for providing an economical means of performing standard creep experiments. Creep tests are performed to study the nonlinear viscoelastic behavior of epoxy resin and {unidirectional (θ=0o) and woven fabric (θ=0o, 90o)) E-glass/epoxy composite materials under various environmental effects at room temperature and different values of applied stresses. Tested specimens are immersed in three different solutions {acidic water (HCL), PH=5), (distilled water (H2O), PH=7}, and {Alkaline water (NaOH), PH=10}. The experimental creep data can be fitted with general power time function. This function is modified where the effect of gained moisture content, applied stress and aged time on the creep strain are suggested as variables in the creep strain equation. Results show that the creep strain increased with increasing the (pH) level and increased more with increasing the values of the applied stress. Also, the results show that the alkaline water “NaOH solution” is more effective than other solutions on the composite viscoelastic behavior. The concluded degradation rates are 36%, 57% and 62.633% for epoxy, woven fabric composite (Mat) (θ= 0o,90o), and unidirectional composite (θ= 0o), respectively. The developed equation gives an appropriate criterion for describing long time creep strain.